% IMPORTANT: The following is UTF-8 encoded. This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.
@PHDTHESIS{Stoffel:82855,
author = {Stoffel, Ralf Peter},
othercontributors = {Dronskowski, Richard},
title = {{V}oraussetzungsfreie {T}hermochemie kristalliner
{F}estkörper},
address = {Aachen},
publisher = {Publikationsserver der RWTH Aachen University},
reportid = {RWTH-CONV-143211},
pages = {VI, 79 S. : Ill., graph. Darst.},
year = {2012},
note = {Aachen, Techn. Hochsch., Diss., 2012},
abstract = {This work deals with an approach to calculate thermodynamic
data without the need of experimental measurements. The data
obtained can complete, verify or falsify experimental data
used in thermochemical calculations. The Gibbs free energy
is constructed from the Helmholtz free energy, because the
theoretical calculations are carried out at constant volume.
Temperature dependent contributions to the Helmholtz free
energy were mainly based on the simulation of lattice
dynamics. Some other smaller contributions were also
included. In the first part the calculated data are compared
with well-known experimental data to verify the method used.
Temperature dependent heat capacities and entropies of some
binary oxides showed good agreement with the data base
values. Theoretically calculated vibrational spectra showed
a good reproduction of Raman spectroscopic measurements in
the case of Barium peroxide. Also mechanical properties,
namely the bulk modulus of Barium oxide, showed good
agreement with experimental values. The phase transition
temperature of tin (alpha to beta) showed a small
overestimation. Part two of the work deals with several more
complex systems. These play a role by modeling the
conditions of fabrication of the high temperature
superconductor YBa2Cu3O6+x. The compounds were BaY2O4,
Ba3Y4O9, BaCeO3, and the superconductor YBa2Cu3O6+x itself.
The first three compounds were necessary to prove the
reliability of the data base, which could be verified in
most cases. In some cases there have to be made at least
some critical considerations. Investigations of YBa2Cu3O6+x
included the structure, which depends on Oxygen content x
and temperature, the heat of formation and the Gibbs free
energy of formation. The temperature and pressure dependent
phase transition between the orthorhombic and tetragonal
modification of YBa2Cu3O6.5 was obtained in good agreement
with the literature. The Gibbs free energy of formation of
YBa2Cu3O6+x from binary oxides and oxygen showed good
agreement with a greater stabilization of the
superconducting phase compared to an equation fitted to
several thousand experimental values.},
keywords = {Ab-initio-Rechnung (SWD) / Thermochemie (SWD) /
Gitterdynamik (SWD) / Festkörperchemie (SWD) /
Dichtefunktionalformalismus (SWD)},
cin = {150000 / 151110},
ddc = {540},
cid = {$I:(DE-82)150000_20140620$ / $I:(DE-82)151110_20140620$},
typ = {PUB:(DE-HGF)11},
urn = {urn:nbn:de:hbz:82-opus-42426},
url = {https://publications.rwth-aachen.de/record/82855},
}
guest ::